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Re: [Libjpeg-devel-6x] YUYV422 to JPEG without additional conversation to RGB using LIBJPEG library?
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From: 陳立格 <b89...@nt...> - 2013-05-11 15:16:44
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郵件討論區留一個備份
於 2013/5/11 下午 10:58, 陳立格 提到:
> 你好:
>
> 是的 真的可以這樣搞.
>
> 不過需要一些修改.
>
> 增加以下代碼
>
>
> turbojpeg.h :
>
> /**
> *
> *
> * Compress an YUV image into a JPEG image.
> * the input data is assumed as aligned as 4.
> * NOTE : the function will not allocate output buffer(pJpegBuf).
> */
>
> DLLEXPORT int DLLCALL tjCompressYUV420(tjhandle handle, unsigned char
> *pY,
> unsigned char *pU, unsigned char *pV, int width, int height,
> unsigned char *pJpegBuf,
> unsigned long *pJpegSize, int jpegQual);
>
>
>
> turbojpeg.c:
>
> #define MAX_LINES (2*DCTSIZE)
> #define DIV2(VAL) ((VAL)>>1)
>
> DLLEXPORT int DLLCALL tjCompressYUV420(tjhandle handle, unsigned char
> *pY,
> unsigned char *pU, unsigned char *pV, int width, int height,
> unsigned char *pJpegBuf,
> unsigned long *pJpegSize, int jpegQual)
> {
> int retval;
>
> getinstance(handle)
> if((this->init&COMPRESS)==0)
> _throw("tjCompress2(): Instance has not been initialized for
> compression");
>
> retval = 0;
> if(setjmp(this->jerr.setjmp_buffer))
> {
> /* If we get here, the JPEG code has signaled an error. */
> retval=-1;
> goto bailout;
> }/*if setjmp(this->jerr.setjmp_buffer)*/
>
>
> cinfo->image_width = width;
> cinfo->image_height = height;
> cinfo->input_components = 3;
> cinfo->jpeg_color_space = JCS_YCbCr;
> cinfo->data_precision = 8;
>
> jpeg_set_defaults(cinfo);
>
> cinfo->in_color_space = JCS_YCbCr;
> cinfo->raw_data_in = TRUE;
>
> jpeg_set_quality (cinfo, jpegQual, TRUE);
>
> cinfo->comp_info[0].h_samp_factor = 2;
> cinfo->comp_info[0].v_samp_factor = 2;
> cinfo->comp_info[1].h_samp_factor = 1;
> cinfo->comp_info[1].v_samp_factor = 1;
> cinfo->comp_info[2].h_samp_factor = 1;
> cinfo->comp_info[2].v_samp_factor = 1;
>
> *pJpegSize = tjBufSize(width, height, TJSAMP_420);
>
> jpeg_mem_dest_tj(cinfo, &pJpegBuf, pJpegSize, 0);
>
> jpeg_start_compress(cinfo, TRUE);
>
>
> {/*variables block */
>
> unsigned int i, j;
> unsigned int widthStepY;
>
> unsigned int endHeight;
>
> JSAMPROW YArrow[MAX_LINES], UArrow[DCTSIZE], VArrow[DCTSIZE];
> JSAMPARRAY encodeYUV[3];
> unsigned char *pMovY, *pMovU, *pMovV;
>
> widthStepY = TJPAD(width);
> endHeight = (height + (MAX_LINES - 1)/ MAX_LINES)*(MAX_LINES);
>
> pMovY = pY; pMovU = pU; pMovV = pV;
>
> for(j = 0; j< endHeight; j+= MAX_LINES){
>
> for(i = 0;i < MAX_LINES; i++)
> YArrow[i] = pMovY + i*widthStepY;
>
> for(i = 0;i < DCTSIZE; i++){
> UArrow[i] = pMovU + i*DIV2(widthStepY);
> VArrow[i] = pMovV + i*DIV2(widthStepY);
> }/*for i*/
>
> encodeYUV[0] = YArrow;
> encodeYUV[1] = UArrow;
> encodeYUV[2] = VArrow;
>
> jpeg_write_raw_data(cinfo, encodeYUV, MAX_LINES);
>
> pMovY += MAX_LINES*widthStepY;
> pMovU += DCTSIZE*DIV2(widthStepY);
> pMovV += DCTSIZE*DIV2(widthStepY);
> }/*for j*/
>
> }/*variables block */
>
>
> jpeg_finish_compress(cinfo);
> bailout:
>
> return retval;
> }/*tjCompressYUV420*/
>
>
> 這樣就可以了
>
>
>
> English:
>
> You should add turbojpeg.h and turbojpeg.c as above, that is what you
> wish. but the proformance is not good as inputing RGB directly, the
> RGB one is better. you should benchmark it.
>
>
>
> 於 2013/5/7 下午 11:53, netmonitoring 提到:
>> Is it possible to save YUYV422 buffer as JPEG using LIBJPEG library
>> without additional conversation to the RGB24/RGB32 color format?
>>
>> Are there examples?
>>
>>
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>
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